Milling curved contours. Locksmith marking - marking How to mark parts with curved
The top is the main decorating part of any jewelry. The size and shape of the top determines the type of product, size, quantity, shape and location of the stones. Its design depends on the sample and the decision of the master. The top may be assembled from castes; smooth, made of rolled metal, with and without castes, karmazirovanny (karmaziring - a dense cluster of stones at the top); openwork, carved in on-board with various fixing stones. The tops are made according to the finished sample, drawing or drawing, made at a scale of 1: 1, or specific sizes.
The top of the castes is flat (not having a common bulge) can be collected on the letlet by successively soldering one caste to another. If the castes do not have to fit snugly together, they are soldered on the veins. The lower base of the caste is inserted with a jigsaw diagonally to the depth of the vein (rolled on the plane of the wire) and mounted on it. The vein is preliminarily bent according to the location of the casters, then the castes are placed on it with the necessary interval and soldered to the vein. With a multi-row arrangement, several castes assembled on the veins are soldered together.
The tops having a common curvature (convexity) are conveniently assembled on a mounting mass, which can be a mixture of kaolin with asbestos or refractory gypsum. The kaolin-asbestos mass softened with water is molded in the shape of the apex and is seated with castes as indicated on the sample. Places of soldering are fluxed with a liquid solution and dried with a burner. With a large number of rations, it is advisable to solder with sawed solder, which, with uniform heating of the product, allows all joints to be simultaneously soldered. The assembled top with the mounting mass is placed in water, the mass softens and can be used in the next assembly.
To assemble the apex on a plaster mass from plasticine, a mold of the desired shape is made and seated in the same manner as in the previous case. Then, a cut in the shape of the top is made in a piece of cardboard and put on the mold so that the top slightly rises above the platform. After this, the top is poured with gypsum mortar (the solution is compacted with a light tapping on the mold), the cardboard pad protects the solution from dripping. The cast, cast in plaster, set the top up to the complete hardening of the solution. Then the clay mold is separated from the hardened gypsum and the cardboard is removed. The bare bases of the casings are degreased, fluxed and soldered. After soldering, gypsum is dissolved in hot bleach (in a separate bleach) and washed with a stiff brush in water.
The top is considered smooth (Fig. 81), if it is made of rolled metal without castes (for decoration with engraving, black enamel for enamel) or as a rim around the caste (several castes). The thickness of the rental for a smooth top is taken depending on the given weight of the product, but not thicker than 0.7 mm. The manufacture of flat tops is elementary - at the hire, draw its contour, cut it out and filed along the contour. But, as a rule, the apex has a curved surface (convexity, and sometimes concavity). The manufacturing process is as follows.
On a flat bar, annealed and then darkened (during annealing in air, the metal is covered with a dark oxide film), the outline of the tip is drawn, and if casting is planned in it, then mark this immediately. The workpiece is cut along the contour and filed. Depending on the shape of the contour, the top and curvature of the surface, it coils (gives curvature) in the anch (Fig. 82), a lead matrix or a tree with punzels - rods with a spherical working part. With complex or deep drawing, the billet is subjected to intermediate annealing, and after completion of this operation, to the final one. The resulting surface curvature is corrected so that the apex contour is parallel. For most products, the top contour should be in the plane, and for bracelets and sometimes rings, it should be bent inward. In the first case, the top is corrected on the dressing plate, in the second - on the crossbar of the corresponding diameter. The base of the top is finished with files and files until the appearance of an evenly wide belt. If the apex is marked for placement of castes, then holes are cut out in it, into which pre-made and processed castes are inserted. In the case when the caste should be located in the apex with a clearance, it is placed on the veins, which are either pre-soldered to the castes, or left during the cutting of the hole, and the hole in the apex is made larger by the width of the clearance. Castes are tightly packed into the holes and soldered.
The top of karmaziring (Fig. 83), as a rule, is a stone seated around smaller stones. For the manufacture of this top use rolled 1.2-1.3 mm. The task should be to determine the fixing of the central and shrink stones. In the case where the central stone needs to be fixed in a blind caste, and shrinkage stones - directly at the apex - in the fountain-grisant, the initial stage of production proceeds similarly to the production of a smooth apex until the holes for the stones are cut. Drilling occurs by marking immediately for all stones. The hole for the central cast, made in advance, is cut out first of all, and the castes are sucked into such a depth so that its lower base does not extend beyond the inner (back) surface. Then, holes for small stones are cut out with a jigsaw, and each hole must correspond to the shape of its “own” stone. The holes are made conical with a narrowing of 20 °. For stones with a perfectly round shape, holes are drilled to a certain depth (nest depth) with a sharpened drill or a special conical milling cutter (boron). The distance between the stones must be coordinated with the variant of the layout of the future fastening.
In the individual performance of products, in addition to the front side of the top, the reverse side is also processed. Processing consists in the fact that all openings for small stones sharply increase with a jigsaw, as a result of the opening they take the form of a funnel log. Jewelers call this operation “cutting openwork under a stone”. Openwork can be of any shape, but should be combined with the shape of the apex and the arrangement of stones. A number of holes cut in such a way form a beautiful pattern (Fig. 84), viewed only from the inside of the product. However, the openwork is not so much for beauty, but in order to open the access of light to the stones and facilitate their washing.
Openwork cut-out top (Fig. 85) is also made of rolled metal with a thickness of 1.2-1.3 mm. The stones at the top can be fixed in castes, czars and directly in the metal of the top-kushka (in the cut out elements of it). At first, as usual, the tsars and castes are made, and then they start marking the tops, which are still carried out on a flat roll. The marking should be clear and deep enough so that after the coveting, its lines are preserved. Further, as in previous cases, the top is cut out along the outer contour, filed, coiled and ruled. Then cut holes for castes and paste them. If the tsars (according to the figure) are planted on the veins, they are inserted after processing the cut pattern of the apex. The holes for the casings, and then for the stones, are cut in sequence from large to smaller, and only after all the holes have been fitted into the stones, the pattern itself is cut out. The openwork pattern is treated with needle and specially sharpened needle files, in the same place where it is impossible to get these needle files, a pure-finish processing is carried out with a jigsaw. After processing the slotted pattern, openwork under the stones is cut from the front and back sides. The assembly of the top with castes is carried out in such a way that the already soldered castes or tsars do not interfere with the soldering of the following.
The typesetting tops are made up of separately made elements: castes, all kinds of overlays, curls, corners, etc.
A set of elements is produced, as a rule, around a caste. Elements soldered by one side to the caste on the other side rest on the welt, forming well-viewed patterns from above.
Fig. 86 shows a ring with a stacked top and its parts.
A welt is a lower contour rim soldered to a caste or top. In its form, in most cases, it copies the contour of the apex, but does not go beyond its size in size. The welt does not significantly increase the height of the apex in height and leaves its reverse side open. It is used for all types of products.
A blank for the welt is a flat pro-cat (0.8-1.0 mm thick), slightly exceeding the size of the apex. The blank must be tightly fitted to the base of the top-hook and soldered with tin in two or three places. The soldered billet is cut along the contour of the top and filed flush. The plate, already having an external contour of the welt, is separated by heating from the top and completely clean the tin from both parts. The inner contour of the welt is marked with a compass at a distance of 1.5-2.0 mm from the outer contour. Thus, the preliminary width of the welt will be 1.5-2.0 mm. The opening of the welt is cut along the intended inner contour, which is then filled.
To the tops intended for rings, the variety of welts is somewhat wider than for other products (Fig. 87). In particular, under the top having a flat base, the welt can be made curved (on the finger), it serves as a transition from the top to the ring splint. In the manufacture of such a welt, its width (distance along the bend) is taken 1.5–2.0 mm less than the width of the top. High welts for rings are made of rolled steel according to the type of a conical caste and raskochat on the contour of the top without going beyond it. The height of such a welt is set by the sample.
Collect the top with welt soldering, in most cases on the veins. Veinspieces of round and rolled wire or tubular workpiece can serve. The cross section of the veins is determined by the distance by which the apex must be separated from the welt. The segments for the veins are soldered to the welt. The number of veins and the distance between them are selected depending on the size of the product and its contour. For the tops, seated with small stones, the veins are soldered so that each vein is under the top stone. The veins soldered to the welt run the flush face with the inner contour of the welt, and on the outside, they are cut off after assembly with the top. Then the welt is tied to the top and all the veins are soldered to it, after which the assembled assembly is processed along the outer contour. The veins extending beyond the contour are cut off, and the contour of the node is filed.
Dikel (Fig. 88) is a variation of the welt. It does not go beyond the horizontal dimensions of the apex, but, being convex, increases in size more in height and covers a significant part of the reverse side of the top. If the dicel is made smooth, then in the center it should have a significant cut in the shape of the apex; if it is openwork, then the central cut can be smaller. The openwork pattern of the dikel is selected if possible so that the reverse side of the stones fixed in the apex is open for washing.
Dikel is mainly used for rings and earrings.
The size of the dichel is determined by the contour of the apex. It is made from rolled products with a thickness of 0.7-0.9 mm. The markup is carried out on a flat workpiece. If the dikel is deaf, they mark the central hole, and if it is openwork, the whole pattern. The base of the workpiece is flushed onto a plane and adjusted to the top of the base. The pattern is cut out with a jigsaw and processed with a file.
When assembling the tops with dikel, the veins are used mainly for deaf dikels, which are sometimes connected to the tops through the veins. In all other cases, the dikel is soldered directly to the top with the whole base or with individual sections of the delicately cut base.
- "onclick \u003d" window.open (this.href, "win2 return false\u003e Print
Drawing Basics
You already know that for the manufacture of any product you need to know its device, the shape and dimensions of the parts, the material from which they are made, methods of connecting parts to each other. You can learn all this information from drawing, sketch or technical drawing.
Drawing
- this is a conditional image of the product, made according to certain rules using drawing tools.
The drawing shows several types of products. Views are performed based on how the product is observed: front, top or left (side).
The name of the product and parts, as well as information on the quantity and material of the parts, is entered in a special table - specification.
Often the product is depicted enlarged or reduced compared to the original. But despite this, the dimensions on the drawing are real.
A number that shows how many times the actual sizes are reduced or increased is called scale
.
The scale cannot be arbitrary. For example, for increase
accepted scale 2:1
, 4:1
etc., for decreasing
-1:2
, 1:4
etc.
For example, if the inscription " M 1: 2
", Then this means that the image is half the actual size, and if" M 4: 1
", Then four times more.
Often used in production sketch
- hand-drawn image of the subject according to the same rules as the drawing, but without observing the exact scale. When drawing up a sketch, the ratio between the parts of the subject is preserved.
Technical drawing - visual image of the item, made by hand in the same lines as the drawing, indicating the dimensions and material of which the product is made. It is built approximately, by eye, maintaining the relationship between the individual parts of the subject.
The number of views in the drawing (sketch) should be such as to give a complete picture of the shape of the subject.
There are certain rules for sizing. For a rectangular part, dimensions are applied as shown in the figure above.
The size
(in millimeters) put down from the dimension line from left to right and from bottom to top. The name of the unit of measure is not indicated.
Part thickness
denoted by a latin letter S; the figure to the right of this letter shows the thickness of the part in millimeters.
The designation on the drawing also applies to certain rules. hole diameter
- it is designated by a symbol Ø
.
Circle radii
denoted by a latin letter R; the figure to the right of this letter shows the radius of the circle in millimeters.
Detail outline
on the drawing (sketch) must be shown solid thick main lines (lines of the visible contour); dimension lines
- solid thin; invisible outline lines
- dashed; axial
- dot-and-dash etc. The table shows the different types of lines used in the drawings.
|
Read the drawing, sketch, technical drawing - means to determine the name of the product, the scale and image of the species, the size of the product and individual parts, their name and quantity, shape, location, material, type of connection.
Technical documentation and harmonization tools
Technical documentation for the manufacture of a simple one-part, multi-part or complex product includes:
picture
finished product, specification and brief information about the function ( F), constructions ( TO), technologies ( T) and decoration (aesthetics) ( E) of this object of labor - the first sheet;
scheme
possible options for changing the overall dimensions and configuration of the product or its parts. The proposed changes are based on various systems of correlation and division of forms - the second sheet;
detail drawings
complex configuration, which are made according to the templates - the third sheet (not for all products);
illustrative technological map
containing information about the sequence of manufacturing of parts or the product itself in the form of operational drawings and about tools and devices used in this operation, the following sheets. Their contents can be partially changed. These changes relate mainly to the use of special technological devices to speed up the execution of certain operations (marking, sawing, drilling, etc.) and to obtain better parts and products.
The development of the design of any product, the appearance of which has certain aesthetic requirements, is associated with the use of certain laws, techniques and means of composition. Ignoring at least one of them leads to a significant violation of the form, making the product inexpressive and ugly.
Most often, harmonization tools such as proportionality (finding the harmonic relationship of the sides of the product), subordination and dismemberment of the form.
Proportionality - this is the proportionality of the elements, the most rational ratio of parts between each other and the whole, giving the subject harmonic integrity and artistic completeness. Proportions establish a harmonious measure of parts and the whole with the help of mathematical relations.
A system of rectangles with a proportional aspect ratio can be constructed using:
but) integer relations from 1 to 6 (1: 2, 1: 3, 1: 4, 1: 5, 1: 6, 2: 3, 3: 4, 3: 5, 4: 5, 5: 6) (Fig. 1) ;
b) the so-called golden ratio". It is determined by the formula a: b \u003d b: (a + b). Any segment can be proportionally divided into two unequal parts in this regard (Fig. 2). Based on this relationship, you can build or dismember the sides of the rectangle (Fig. 3);
at) proportional seriesmade up of the roots of natural numbers: √2, √3, √4 ”√5. You can build a system of rectangles of this series as follows: on the side of the square “1” and its diagonal “√2” - a rectangle with an aspect ratio of 1: √2; on the diagonal of the latter - a new rectangle with an aspect ratio of 1: √3; then the rectangle is 1: √4 (two squares) and 1: √5 (Fig. 4).
To find the harmonic aspect ratio use the system subordination and dismemberment of the form:
but) subordination it is applied when another, proportionate to the main part is attached to some element (Fig. 5);
b) the dismemberment is used when it is necessary to divide the main form into smaller elements (Fig. 6).
Below are options for changing the configuration of the shape of the products and options for changing the overall dimensions, in which the above harmonization rules are used.
Marking rectangular parts
The purpose and role of the markup. The process of applying contour lines to the future workpiece on wood is called marking. Markup - one of the most important and time-consuming operations, on the performance of which not only the quality of the products, but also the cost of the material and working time largely depends. Marking before sawing is called preliminary or marking up rough blanks.
In production, preliminary marking is carried out taking into account processing allowances and shrinkage. In training workshops, dried materials are processed, therefore, allowances for shrinkage are not taken into account.
You should be aware that when processing dried workpieces, a surface with a low roughness is obtained and high adhesion and finish are achieved. Grinding allowances on the one hand, the details of planed surfaces are 0.3 mm, and for parts whose surfaces are sawn, - not more than 0.8 mm. Allowances for planing wood-fiber boards and glued plywood are not provided, as they are not subject to planing.
Markup perform in pencil using marking tools (measuring ruler, joiner's square, surface gage, malka, tape measure, vernier caliper, etc.) in accordance with the drawing, sketch, technical drawing. A general view of some marking tools is shown below.
Marking and measuring tools. As you already know, the marking of wood and wood materials is carried out with various tools, most of which are also used for measurements in the manufacturing process of parts: roulette - for measuring and marking saw and timber; meter- for marking rough blanks; ruler - for measuring parts and blanks; square - for measuring and plotting rectangular parts; nonsense - for drawing and checking angles of 45 ° and 135 ° and when marking joints on the "mustache"; malka- for drawing and checking various angles (a given angle is set by the protractor); surface gage and bracket - for drawing parallel lines when processing edges or layers of workpieces; compass - for drawing arcs, circles and deferring sizes; calipers - to determine the diameter of round holes; caliper - for measuring the diameter of the holes.
From precision markup product quality depends. Therefore, be careful when working. Try to keep the marking so that as many parts as possible are obtained from one workpiece.
Do not forget about allowance. Allowance
- a layer of wood that is removed during processing of the workpiece (when sawing, they usually give an allowance of up to 10 mm, with planing - up to 5 mm).
When marking a rectangular piece of plywood (Fig. but
) do this:
1. Choose base edge blanks (if there is no such edge, then it should be cut according to previously applied on a ruler baseline).
2. A line is drawn along a square at right angles to the base edge (line) at a distance of about 10 mm from the end (Fig. b
)
3. The length of the part is laid off from the drawn line along the ruler (Fig. at
).
4. A line is drawn along the square limiting the length of the part (Fig. g
).
5. On the ruler, lay the width of the part on both lines, limiting the length of the part (Fig. d
).
6. Connect both received points (Fig. e
).
If the part is made of a board or bar, then the marking is made from the most even and smooth layers and edges (if they are not there, then the front layer and edge are pre-strapped). Front surfaces on the workpiece are marked with wavy lines.
Subsequent markup is performed as follows:
1. The width of the part is laid off from the front edge and a marking line is drawn with a pencil (Fig. A).
2. The thicknesser rail is extended so that the distance from the tip of the stud to the shoe is equal to the thickness of the part (Fig. B).
3. Using a thickness gauge, mark the thickness of the part (Fig. C).
4. Mark the length of the part using a ruler and a square (Fig. G).
The marking of a large number of identical parts or parts having a curved contour is carried out using special patterns
. They are made in the form of plates having the same shape as the outline of the product.
Mark out the details with a simple and sharpened pencil.
When marking, the template should be firmly pressed to the workpiece.
The process of manufacturing wood products
In training workshops, they learn to make various products from lumber and plywood. Each of these products consists of individual parts connected together. Parts can have a different shape. First they try to make flat rectangular parts. To do this, you need to correctly select the workpiece (bar, board, plywood sheet), learn how to perform marking, planing, sawing, stripping. After the manufacture of all parts, the assembly and decoration of the product is carried out. Each of these work steps is called operation .
Each operation is performed by a specific tool, often using fixtures . So-called devices that facilitate the work and make it better. Some devices help, for example, quickly and reliably fasten a part or workpiece, tools, others accurately mark out, without errors to perform this or that operation. It is advisable to use the devices in the case when you need to make a large number of identical parts. You are already familiar with one of the fixtures - the clamp of a carpentry bench.
In the training workshop, you will most often work on technological map which indicates sequence of operations . Below is a flow chart of the manufacture of a kitchen board.
|
Technological maps used in production indicate all operations, their components, materials, equipment, tools, the time required to manufacture the product, and other necessary information. In school workshops, simplified technological maps are used. They often use various graphic images of products (technical drawings, sketches, drawings).
The finished product will be of high quality if it meets the dimensions and requirements indicated on the drawing.
To obtain a high-quality product, it is necessary to hold the tool correctly, observe the working position, accurately perform all operations, constantly monitor yourself.
Not all machine parts have contours outlined in straight lines, similar to those discussed in previous chapters; many parts represent flat surfaces bounded laterally by curved contours. In fig. 222 shows parts with curved contours: a wrench (Fig. 222, a), a clamp (Fig. 222,6), a cam to a turning machine (Fig. 222, c), a connecting rod of the engine (Fig. 222, d).
The curvilinear contour shown in Fig. 222 parts consists of straight segments, conjugated with curves or with arcs of circles of various diameters, and can be obtained by milling on a conventional vertical milling machine or a special copy-milling machine.
Curved path millingon a vertical milling machine can be carried out: for marking by combining manual feeds, for marking with a round rotary table and a copy.
Milling a curved contour by combining manual feeds. Milling by combining manual feeds consists in the fact that the pre-marked workpiece (fixed either on the table of the milling machine, or in a vice, or in a special tool) is processed with an end mill, moving the table with manual feed simultaneously in the longitudinal and transverse directions so that the cutter removes the metal layer in accordance with the marked curved contour.
Consider the example of milling by marking by combining manual feeds of the contour of the bar shown in Fig. 223.
The choice of cutters.For milling, we choose an end mill, the diameter of which would make it possible to obtain a rounding of R \u003d 18 mm, required by the drawing. We take an end mill with a diameter of 36 mm with six teeth. The material of the cutter is high-speed steel.
Preparation for work. The bar is installed directly on the table of the vertical milling machine, securing it with tacks and bolts, as shown in Fig. 224. A parallel lining is used so that the cutter during processing does not touch the working surface of the machine table.
When installing, make sure that chips or dirt do not get between the contacting surfaces of the machine table, lining and parts.
Setting the machine to cutting mode. Since for our case the feed is carried out manually, we take it equal to 0.08 mm / tooth, considering the cutting depth of 5 mm. According to the table 211 of the “Manual of a young milling machine operator” for these conditions, the recommended cutting speed is 27 m / min and the corresponding number of mill revolutions is n \u003d 240 rpm.
We select the closest number of revolutions available on the machine and set the speed box limb at n \u003d 235 rpm, which corresponds to a cutting speed of 26.6 m / min.
Contour milling. We will carry out milling with manual feed, following the marking, for which we will begin processing from the area where there is the smallest allowance, or we will embed gradually, in several passes, in order to avoid breakage of the cutter.
Milling is performed by simultaneous feeding in the longitudinal and transverse directions, respectively, of the marking line. It is not possible to mill a contour cleanly in one pass, therefore, first a curved contour is milled rough, and then cleanly along a marking line, including rounding off at a wide part of the bar.
Milling the central groove 18 mm wide and 50 mm long is carried out according to the method of milling a closed groove (see Fig. 202).
Curved contours having the shape of a circular arc in combination with straight line segments or without them are processed on a round turntable (see Figs. 146 and 147).
When machining on a round rotary table, an arc contour is formed without combining two feeds as a result of a circular feed of the rotary table, and the accuracy of the contour here does not depend on the ability to combine two feeds, but on the correct installation of the workpiece on the table.
Consider an example of milling a part that combines the processing of the outer contour with the processing of internal circular grooves.
Let it be necessary to process the contour pattern shown in Fig. 225.
The blank has the form of a rectangle with a size of 210 × 260 mm and a thickness of 12 mm. A central hole with a diameter of 30 mm (for fixing it on a round table) and four auxiliary holes with a diameter of 30 mm (for milling) were pre-drilled in the workpiece. The part outline is marked on the workpiece.
Milling will be carried out on a vertically milling machine. Since external and internal contours are subject to processing, milling must be performed in two installations:
1. Having fixed the workpiece on the round table with bolts passing through any two holes on the workpiece, we mill the external contour according to the marking using the rotational movement of the round table (Fig. 226, a).
2. Having fixed the workpiece on the round table with clamping bars, we mill the internal circular grooves according to the marking, using the rotational movement of the round table (Fig. 226,
Since the processing of the external contour and internal grooves is desirable to be performed without changing the cutter, we select an end mill made of high-speed steel with a diameter of 30 mm corresponding to the width of the circular groove.
Before installation, the round table must be placed on the edge and wipe its base. Then insert clamping bolts with nuts and washers on both sides of the machine table and fasten the round table with bolts. To base the workpiece, it is necessary to insert a centering pin with a diameter of 30 mm into the central hole of the round table.
We fix the workpiece with a centering pin and bolts during the first installation (Fig. 226, a) and a centering pin and clamps during the second installation (Fig. 226, b).
Setting the machine to milling mode. Choose the cutting speed according to the table. 211 of the “Handbook of a young milling machine operator” for a mill with a diameter of 30 mm and feed for £ tooth \u003d 0.08 mm / tooth, with the largest cutting depth t \u003d 5 mm. Cutting speed v \u003d 23.7 m / min and, accordingly, n \u003d 250 rpm.
We adjust the machine to the nearest number of revolutions p \u003d 235 rpm, which corresponds to a cutting speed of v \u003d 22.2 m / min, and proceed to the processing of the outer contour.
Having fixed the end mill in the machine spindle, turn on the machine and bring the part to the mill in the place where there is the smallest allowance (Fig. 226, a).
The rotary cutter is cut by manual feed into the workpiece to the marking line and, by turning on the mechanical longitudinal feed, the straight section 1-2 is milled (Fig. 225). With manual rotation of the round table, a curved section 2-3 of the outer contour is milled. After that, with a mechanical longitudinal feed, a rectilinear portion 3-4 of the outer contour is milled, and finally again, with a manual rotation of the round table, a curved portion 4-1 of the outer contour is milled.
Installation of the workpiece for milling circular grooves is performed as shown in Fig. 226 b
By rotating the handles of vertical, longitudinal and transverse feeds, a mill is brought (see Fig. 226, b) and inserted into hole 5 (see Fig. 225). Then they raise the table, lock the console of the table and smoothly manually rotate the round table, slowly rotating the handwheel, mill the internal groove 5-6. At the end of the passage, lower the table to its original position and bring the cutter out of the groove. By turning the knobs of the circular and vertical feeds, a mill is introduced into the hole 7 and the inner groove 7-8 is milled in the same way by a circular feed.
Copy milling. Milling of parts having a curved contour, curved grooves and other complex shapes can be performed, as we have seen, either by combining two feeds, or by using a rotary round table; in these cases, preliminary marking is required.
In the manufacture of large batches of identical parts with a curved contour, special copying devices are used, or special copy-milling machines are used.
The principle of operation of copying devices is based on the use of longitudinal, transverse and arc feed of the machine table to communicate to the workpiece a curvilinear movement that exactly matches the contour of the finished part.
To automatically obtain this contour, copiers are used, i.e. templates that replace the markup. In fig. 227, b shows the milling of the contour of the large head of the connecting rod of the engine. The copier 1 is placed on part 2 and securely fastened with it. Acting with the handwheel of the circular feed of the round turntable and the handles of the longitudinal and transverse feeds, the milling machine ensures that the neck 3 of the end mill is constantly pressed to the surface of the copier 1.
copy processing,
The end mill used for is shown in fig. 227, a.
In fig. 228 is a diagram of a copying device for milling the contour of a large head of a connecting rod of an engine similar to that shown in Fig. 227, but with the use of, except for the copier, another roller and cargo. Under the action of the load 1, the roller 2 is always pressed against the copier 5, rigidly connected to the table of the copying device 5, on which the machined connecting rod is fixed 4. The mill 3 will describe the curved path corresponding to the contour of the large connecting rod head, if, using a circular feed, we will rotate a round rotary table .
Marking - the initial operation of the process of processing parts of the body. The layout receives sheets and profiles, the details of which will be cut on mechanical equipment, portable machines for thermal cutting or manual gas cutters. Marking can be done manually, using photoprojection, outline or template methods, on marking and marking machines with programmed control and using other methods.
The photoprojection method is used for marking sheet metal parts. With this method, negatives from large-scale drawings-templates are issued to the section of the shop marking. * The life-size marking of the contours of parts on the material is carried out according to the image from the negatives using special projection equipment.
The actual markup process is as follows. A metal sheet is served on a marking table. If the sheet does not lie on the table loosely (there are gaps between the sheet and the table top), then it is pressed against the table with clamps. The projection equipment is turned on, in which the corresponding negative is inserted in advance, and it is tuned. Since the lines and signs of the large-scale drawing are drawn in black ink, on the negative and its projection these lines and signs turn out to be light. On the light lines and signs on the surface of the marked sheet fix (core) the contours of the parts and their marking.
The sketch method of marking is used mainly for marking parts from profile steel. The use of this method for sheet metal parts is allowed only in cases of marking volumetric waste, the absence of photoprojection equipment and marking and marking machines.
The marking of parts with the help of sketches is reduced to the fact that the marker builds on the sheet or profile in full size the contours of the parts depicted in the sketches. The contours of the parts are obtained by performing simple geometric constructions using conventional measuring and marking tools. For marking the most complex parts, rails or templates are attached to the sketches, which is specially stipulated in the sketches. Both sketches and slats, as well as templates, come to the workshop markup area from the plaza.
Marking according to the patterns are subjected to parts having curved edges, the construction of which in a geometric way presents significant difficulties, as well as parts from bent profiles.
Mark the details according to the templates as follows. A template is laid on the sheet to be marked. After that, the outline of the part along the edges of the template is scribbled. Then they cut out all the cutouts on the template. Next, the template is removed and marked parts. After that, break lines, welds and all other lines necessary for processing and assembling parts are punched or drawn (according to serifs).
Fig. 11.5. Measuring tool: a - steel tape; b - folding meter; in - caliper; g - micrometer.
As a measuring tool when performing marking works, apply (Fig. 11.5):
- tape measures with a metal tape up to 20 m long, metal rulers up to 3 m long, folding meters for measuring lengths;
- calipers and calipers for measuring internal and external diameters, as well as material thickness with an accuracy of 0.1 mm;
- goniometers, protractors for measuring and building angles;
- micrometers for measuring the thickness of the material with an accuracy of 0.01 mm.
Fig. 11.6. Marking tool: a - compass; b - caliper; in - squares; g - marking center punch; d - control punch; e is a thread; Well - surface gage.
As a marking tool, apply (Fig. 11.6):
- compass and caliper for drawing circles and building perpendiculars;
- squares for building perpendiculars;
- cores for drawing points on metal;
- threads for drawing straight chalk lines;
- Thicknessers for parallel lines on the shelves of profile steel, etc .;
- scriber for drawing lines.
All dimensions applied to parts that do not have allowances must correspond to the plaz or drawing.
The following are the values \u200b\u200bof permissible deviations of the actual dimensions of the marked parts from the nominal (in millimeters):
From the overall dimensions for sheet parts:
with a length (width) of up to 3 m .............. ± 0.5
with a length (width) of more than 3 m ............ ± 1,0
From overall dimensions for profile parts:
with a length of up to 3 m .................. ± 1,0
with a length of more than 3 m ................. ± 2.0
From the size of cutouts for a set, etc. ........... 1,0
Diagonal difference ................... 2.0
From straightness or other shape of the edges:
with the length of the edges or chords (with curved edges) up to 3 m .................. ± 0.5
with the length of the edge or chord more than 3 m ........ ± 1,0
When marking, the width of the chalk line should not be more than 0.7 mm. The width and depth of the line drawn by the scriber should not exceed 0.3 mm.
When marking some parts along their edges, allowances are left. An allowance is a part of the metal removed from the workpiece to obtain parts in drawing or plaza sizes. The allowances are intended to compensate for possible deviations from the dimensions that arise during the processing of parts, assembly and welding of assemblies and sections. Values \u200b\u200bof allowances assigned from the conditions for the manufacture of parts are usually taken within 5-50 mm.
To save marking traces until the end of the processing and assembly of parts and restore marking (if necessary), all marking lines are closed.
Light alloy body parts are marked with a simple soft pencil. Punching of only the centers of the holes, the installation locations of the set (subject to mandatory further overlap by their welded parts), as well as contour lines that are removed during subsequent processing, is allowed.
For each marked part, a mark is necessarily applied.
The advent of automatic thermal cutting of parts allowed to exclude the operation of marking these sheets, but the marking of the parts remained. In order to automate the process of marking parts on production lines for thermal cutting of parts, marking machines with program control have been created. A prototype laser marking and marking machine has now been created.
* In detail about drawings-templates it was said in chap. 10.
When processing metal or forgings, some of their surfaces are left in black, and others are removed from the metal layer of a certain thickness so that the treated surfaces have the shape and dimensions indicated on the drawing. Therefore, before starting processing, it is necessary to mark the parts.
Markupthey call the operation of transferring the necessary contour dimensions from the drawing on the plane of the material or workpiece, in order to produce the necessary locksmith processes for the final manufacture of products. Distinguish planar and spatial markings.
Flat marking- this is the application of contour dimensions on the plane of the material from which the part will be made. For example, marking cut air ducts from sheet material, marking flanges, gaskets.
Spatial marking - this is the application of contour lines on the plane of the workpieces, conjugated at various angles. For example, applying the required contours to the volumetric workpiece of a part made with excessive allowances.
In order for the contour lines drawn on the marked surfaces of the workpiece to be clearly visible, these surfaces must first be painted.
Unprocessed or roughly machined planes of cast parts of forgings are first cleaned of dirt, remnants of molding sand, sand, scale, chop off burrs and hot flashes, and then stained with chalk, quickly drying paint or varnished.
For coloring, crushed chalk is dissolved in water (125 g of chalk per 1 liter of water) until the milk is thick, boiled, and then a little linseed oil is added so that the chalk does not crumble, and desiccant accelerates the drying of the paint.
With a solution of copper sulfate (three teaspoons of vitriol in one glass of water) or lumpy copper sulfate, purely treated planes are painted. Liquid solutions are applied to the surface of the workpiece with a brush in a thin layer. In vitriol rub the surface of the workpiece moistened with water. Marking is done after the paint has dried.
In the manufacture of blanks, an allowance for processing is provided in advance.
Allowance- this is an increase in the size of the workpiece in comparison with the contour lines (risks) plotted exactly according to the drawing.
The allowance should be the smallest in order to save material, reduce the time spent on processing the part and increase the labor productivity of the worker. Marking is necessary to ensure that the dimensions of the workpiece and allowances are correct.
Flat marking
Marking works in plumbing are an auxiliary technological operation consisting in transferring contour structures according to the dimensions of the drawing to the workpiece.
Markup- this is the operation of applying to the surface of the workpiece lines (lines) that define the contours of the manufactured part, which is part of some technological operations.
Flat markingused in the processing of sheet material and profile rolled products, as well as parts on which marking risks are applied in one plane.
Plane marking consists in drawing contour lines on the material or workpiece: parallel and perpendicular, circles, arcs, angles, various geometric shapes according to given sizes or contours according to patterns. Contour lines are applied as solid patterns.
In order to keep the traces of the scratches until the end of the treatment, small recesses close to one another are applied to the risks using a punch, or a control risk is applied next to the marking risk. Risks should be subtle and clear.
Spatial marking- this is drawing on the surfaces of the workpiece, interconnected by a mutual arrangement.
Flat marking is done on the workpiece with a scriber. Marking accuracy is achieved up to 0.5mm. Scriber marking risks are carried out once.
The core depth is 0.5mm. When performing a practical task, the scriber and the marking compass can be kept on a bench.
At the end of the work, it is necessary to remove dust and scale from the screed plate with a brush. When performing a practical task, it is necessary to press the ruler to the workpiece with three fingers of the left hand so that there is no gap between it and the workpiece. When sticking long scores (more than 150mm), the distance between the recesses should be 25..30mm. When screwing up short marks (less than 150mm), the distance between the recesses should be 10..15mm. Before setting the compass to the size of the radius of the arc, the center of the future arc must be tilted. To set the compass to size, you need to install one compass leg with a tip on the tenth division of the ruler, and the second - endowment, exceeding the set by 10 mm. Angles less than 90º are measured with a goniometer using a square. With planar marking, parallel risks are applied using a ruler and a square. When marking on a plate a circle of a given diameter, you need to set the compasses to a size exceeding the radius of the circle by 8..10mm.
The following tools are used for marking, measuring and checking the correctness of the manufacture of products: ruler, square, compass, caliper, caliper, caliper, scale and pattern ruler, protractor, scriber, center punch, marking plate. As devices that accelerate the markup process, use templates, patterns, stencils.
Scriberit should be convenient for drawing clear lines on the marked surface and, at the same time, not spoiling the working planes of the ruler, square. Scriber material is selected depending on the properties of the marked surfaces. For example, a brass scriber leaves a clearly visible mark on the surface of the steel. When marking parts from softer materials, it is advisable to use a pencil. Before marking, it is better to apply a thin layer of water-based paint to the plane.
Punchserve for drawing centers of circles and holes on marked surfaces. Cores are made of solid steel. The punch length is from 90 to 150mm and the diameter is from 8 to 13mm.
As a percussion instrument when performing core cavities using a bench hammer, which should have a small weight. Depending on how deep the core recess should be, hammers weighing from 50 to 200 g are used.
Protractorsteel with a goniometer is used for marking and checking angles in the manufacture of mating pipe assemblies, fittings and other parts of air ducts.
Marking compassit is used for drawing circles, arcs and various geometric constructions, as well as for transferring dimensions from a ruler to a marking blank or vice versa. Distinguish compasses are rack, thicknessers, calipers, caliper, calipers.
Marking boardsinstalled on special stands and cabinets with drawers for storing marking tools and devices. Small scribers are placed on tables. The working surfaces of the scribe plate should not have significant deviations from the plane.
Various geometric figures are applied to the plane with the same marking tool: a ruler, a square, a pair of compasses and a protractor. To speed up and simplify planar marking of identical products, sheet metal templates are used.
A template is placed on the workpiece or material and pressed tightly so that it does not budge during marking. Along the contour of the template with a scriber, lines are drawn indicating the contours of the workpiece.
Large parts are marked on the stove, and small parts are in a vice. If the product is hollow, for example a flange, a wooden cork is hammered into the hole and a metal plate is fixed in the center of the cork, on which the center for the compass leg is marked with a punch.
The flange is marked as follows. The surface of the workpiece is painted with chalk, outline the center and draw a circle with a pair of compasses: the outer contour, the contour of the hole and the center line along the centers of the holes for the bolts. Often, the flanges are marked according to the template, and the holes are drilled along the conductor without marking.